arXiv subjects

Nick Feldman

Publications and source records attributed to Nick Feldman.

3 recordsLinked to original sources

arXiv2025

Metasurface lasers programmed by optical pump patterns

Metasurface lasers offer unprecedented control over light emission, yet their spatial and modal characteristics are typically fixed post-fabrication. Here, we introduce a reconfigurable plasmonic metasurface laser platform in which the lasing area geometry, and thus the emission properties, are dynamically programmed via spatially structured optical pumping. Using hexagonal arrays of silver nanoparticles embedded in dye-doped waveguides, we demonstrate lasing at high-symmetry points of the Brillouin zone, including the K and M points. K-point lasing exhibits spontaneous symmetry breaking (SSB) in relative intensity between degenerate K and K' modes, with no bias induced by pump geometry, even for geometries that explicitly break symmetry. In contrast, M-point lasing allows deterministic control over emission channels via asymmetric pumping. We further show that spatially separated K-point lasers synchronize in phase and amplitude, undergoing SSB in lockstep. A theoretical density matrix approach cast into stochastic differential equations reproduces the observed real- and Fourier-space intensity distributions and SSB behavior. Our findings establish spatially programmable metasurface lasers as a versatile platform for exploring dynamic phenomena in photonic lattices, with potential applications in vortex beam shaping, optical logic, and true random number generation.

physics.optics↗

arXiv2025

Blob Detection for Photonic Metasurface Designing: Angular and Spectral Control of Scattered Light

Metasurfaces with precise spectral and angular control of light scattering are of growing interest for photonic applications requiring advanced photon management. Correlated disorder emerged as a promising route for angular control of light scattering, but most design approaches are computationally expensive or do not allow spectral tunability. Here, we introduce a reverse-engineering design approach for correlated-disordered metasurfaces based on tailoring the Fourier space and blob detection to create point distributions that are later "decorated" with individually designed nano-resonators or meta-atoms to tune the optical response for the desired functionality. We validate the control of the angular scattering by fabricating ensembles of Au nanopillars following our design and characterizing their angular scattering with Fourier microscopy. Using finite-difference time-domain simulations, we demonstrate how the choice of decorative unit tunes the spectral response, showcasing individual and independent control over light scattering in angular and spectral terms. Lastly, we expand the limits of our versatile approach by combining multiple metasurfaces in one, effectively adding their individual scattering characteristics. As such, we can address spectral and angular ranges independently, yielding a high degree of control of the scattering response.

physics.optics↗

arXiv2025

Uncovering hidden resonances in non-Hermitian systems with scattering thresholds

The points where diffraction orders emerge or vanish in the propagating spectrum of periodic non-Hermitian systems are referred to as scattering thresholds. Close to these branch points, resonances from different Riemann sheets can tremendously impact the optical response. However, these resonances are so far elusive for two reasons. First, their contribution to the signal is partially obscured, and second, they are inaccessible for standard computational methods. Here, the interplay of scattering thresholds with resonances is explored and a multi-valued rational approximation is introduced to access the hidden resonances. The theoretical and numerical approach is used to analyze the resonances of a plasmonic line grating. This work elegantly explains the occurrence of pronounced spectral features at scattering thresholds applicable to many nanophotonic systems of contemporary and future interest.

physics.optics↗